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Fuel Cell

From RitchieWiki

A fuel cell is an energy generation device that converts fuel, namely hydrogen and oxygen, into electricity through a simple chemical reaction.[1]

A fuel cell is similar to another type of electrochemical device—a battery. Chemicals are stored inside the battery and it converts these stored chemicals into electricity. Eventually, the battery goes dead once the chemicals are used up. The fuel cell, however, unlike a battery, never dies because chemicals are constantly flowing through the cell. As long as there remains a continuous flow of chemicals into the cell, electrical output from the cell will be maintained.[2]

The primary purpose of fuel cells is to produce an electrical current or direct current (DC) electricity that is directed to the outside of the cell to work as an electrical power source that can be used in everything from car motors to light bulb fixtures.[3]

Fuel cells are also scalable, meaning they come in all shapes and sizes and can be used to power both stationary and mobile applications.[4]

A fuel cell can be envisioned as sort of an electrical sandwich with an electrolyte positioned between two oppositely charged metal plates, one called an anode and the other called a cathode.[5]The anode is the negative post of the fuel cell and the cathode operates as the positive post. The function of the anode is to act as a catalyst (a special material that facilitates the reaction of oxygen and hydrogen) and conduct electrons that are freed from hydrogen molecules so they can be used in an external circuit. Channels etched in the anode assist in effectively dispersing the hydrogen gas equally over the surface of the catalyst. The cathode also has the same type of channels etched into it so it can evenly disperse oxygen over the surface of the catalyst. The cathode is also responsible for conducting electrons back from the external circuit to the catalyst. Here, they recombine with hydrogen ions and oxygen to form a byproduct—water.[6] Every fuel cell also has an electrolyte that operates as a proton exchange membrane. Made of a very specially treated material, the function of the electrolyte is to conduct positively charged ions while blocking electrons.[7]

The chemical reaction occurs as follows. Hydrogen is guided towards the catalyst. The catalyst works to break or split the hydrogen atom into protons and electrons. While the protons continue on through the anode, electrons are redirected through a circuit to generate electrical power. Both protons and electrons then meet up on the other side to combine with oxygen that has passed through the cathode. The protons, electrons, and oxygen merge to create water. Heat and water, both byproducts of the fuel cell, can be captured and re-used.[8]

There are different types of fuel cells, but the one type receiving the most focus in terms of developmental capability is the polymer exchange membrane fuel cell (PEMFC). The PEMFC has a high power density and a relatively low operating temperature that ranges between 60 and 80 degrees Celsius, or 140 and 176 degrees Fahrenheit. With its low operating temperature, a PEMFC does not take as long to warm up, making it the most promising fuel cell technology on the market today and the one most likely to power houses and vehicles in the future.[9]

Hydrogen is the basic fuel of fuel cells. All fuel cells require oxygen to produce an electrochemical reaction. This is what makes them such an environmentally friendly and fuel-efficient source of energy. The combination of hydrogen and oxygen generates electricity and the byproduct they generate, water, is completely harmless.[10] Also, with fossil fuels becoming more expensive and in short supply, fuel cells provide a very feasible power alternative, because hydrogen is a source of fuel of which there is a vast supply. The adoption of fuel cell energy may steer us away from a dependence on fossil fuels in the near future, once the technology has been perfected.

There are still a few wrinkles to work out before the adoption of fuel cells goes mainstream. One is cost and the other is durability. Fuel cell systems are still not competitively priced in comparison with gasoline-powered vehicles, costing $35 per kilowatt. Researchers are also still working to develop fuel cell membranes that are highly durable and can perform in temperatures greater that 100 degrees Celsius as well as sub-zero ambient temperatures. This is necessary in order for a fuel cell to have a higher tolerance to impurities in fuel. Current membranes still degrade while fuel cells cycle on and off, especially when the operating temperature increases.[11]